Small-scale magnetic and velocity inhomogeneities in a sunspot light bridge

TL;DR

This study reveals small-scale, dynamic magnetic and velocity inhomogeneities in a sunspot light bridge, identified through high-resolution spectro-polarimetric data, suggesting magneto-convection and potential chromospheric reconnection activity.

Contribution

It provides the first detailed characterization of small-scale magnetic and velocity anomalies in a sunspot light bridge using Hinode data, highlighting their temporal evolution and spatial properties.

Findings

Inhomogeneities are highly time-dependent and localized.

Inhomogeneities occupy less than 10% of the resolution element.

Possible interaction with overlying magnetic fields may lead to chromospheric reconnection.

Abstract

High resolution spectro-polarimetric observations of a sunspot light bridge by Hinode, reveal small-scale inhomogeneities in the magnetic field and velocity. These inhomogeneities arise as a consequence of a weak, secondary lobe in the Stokes V profile which have a polarity opposite that of the sunspot and very large (>5 km/s) Doppler velocities of both signs, suggesting two distinct types of magnetic anomalies. These two sets of inhomogeneities are highly time-dependent and appear exclusively in the upper half of the light bridge and only after the light bridge is completely formed. Both sets of inhomogeneities appear as patches and can be present independent of the other, next to one another, or spatially separated in a single scan. A two-component inversion of the corresponding spectral profiles indicate that the inhomogeneities occupy a very small fraction, amounting to less than 10 %, of the resolution element. These structures are likely driven by small-scale magneto-convection where they could further interact with the overlying sunspot magnetic field to produce reconnection jets in the chromosphere.